Numerous machines have been developed for forming heat sealable bags or pouches from a continuous roll of stock, such as folded thermoplastic sheet material. Most of these known machines form the bag from roll stock, following which the bag is filled, and thereafter the mouth is sealed. Machines of this general type are necessarily of substantial mechanical complexity and size, and hence have been unacceptable in many situations which do not require or justify the use of a machine of this type. The cost and overall mechanical complexity of these machines, and the periodic maintenance thereof, thus make machines of this type unacceptable in many situations.
In order to service those situations wherein machines of the latter type are not acceptable, there have been developed heat-sealing machines which are of minimum size and structural complexity, and hence of substantially less cost. These known machines, which are generally manually actuated, are basically capable solely of heat sealing the mouth of a preformed bag after filling thereof. However, these known machines have also normally been less than satisfactory, either structurally or operationally.
Machines of the latter type which solely seal the mouth of a bag, and hence require the use of preformed bags, have satisfied a demand in the market place, such as the demand of hospitals and the like. However, these known manually-actuated machines possess disadvantages which make their use less than satisfactory. For example, such machines often utilize a foot-actuated pedal and linkage for moving one of the sealing jaws. This is undesirable in view of the additional space required therefor, and the difficulties created when it is desired to position a machine of this type on an existing table or counter. These known machines also conventionally utilize a manually movable upper jaw positioned for clamping engagement with a fixed lower jaw, and this arrangement makes it more difficult to manually position and hold the mouth of the bag between the jaws while simultaneously actuating the upper jaw into clamping engagement with the lower jaw. Still further, most of these known machines utilize an impulse-type heating element for melting and sealing the mouth of the bag, which heating element is more delicate and thus more subject to damage, and additionally requires a greater time period in order to effect proper heat sealing of the bag mouth. Impulse sealers also normally result in a higher temperature, which is also unacceptable for use with some types of sealable bags. Another disadvantage of these known machines is the difficulty associated with providing a controlled yet uniform clamping pressure when the bag mouth is held between the opposed jaws, coupled with a controlled yet optimum period of time during which the bag mouth is exposed to the heating and clamping pressure so as to provide an optimum seal.
Accordingly, it is an object of this invention to provide an improved apparatus which overcomes many of the above-mentioned disadvantages. More specifically, it is an object of this invention to provide an improved apparatus for heat sealing the mouth of a preformed bag or pouch, which apparatus can be manually actuated but provides optimum heating temperature and clamping pressure to provide a desirable seal across the bag mouth, while permitting this sealing operation to be accomplished in a simple and efficient manner.
It is also an object to provide an improved apparatus, as aforesaid, which utilizes a stationary upper heating element of the resistance type which is effectively continuously energized to thereby permit utilization of a lower heating temperature, whereby the apparatus is usable with bags formed of many materials, and which fixed upper clamping jaw coacts with a vertically movable lower clamping jaw to facilitate the insertion of the bag mouth between the jaws and the holding thereof during the heat-sealing operation, and the removal of the sealed bag from the apparatus upon completion of the sealing operation.
A further object is to provide an improved apparatus, as aforesaid, which can be easily manually activated by inserting the bag mouth between the jaws and then manually lifting the lower jaw upwardly, which in turn activates the apparatus so that the lower clamping jaw is held snugly against the stationary upper clamping jaw for a predetermined time at a substantially predetermined pressure, following which the lower jaw is automatically moved downwardly to permit removal of the sealed bag.
Still a further object is to provide an improved apparatus, as aforesaid, which is small and compact, structurally simple, reliable, easy and efficient to operate, relatively inexpensive, lightweight, portable, and can be easily positioned on an existing table, counter or the like.
Other objects and purposes will be apparent to persons familiar with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.